Heat resistant thermoplastic articles including co-stabilizers

ABSTRACT

Disclosed is a molded or extruded thermoplastic article including a polyamide composition including (a) a polyamide resin having a melting point and/or glass transition; (b) 0.1 to 10 weight percent of one or more polyhydric alcohols having more than two hydroxyl groups and having a number average molecular weight (M n ) of less than 2000; (c) 0.1 to 3 weight percent of one or more co-stabilizer(s) selected from the group consisting of secondary aryl amines and hindered amine light stabilizers, and mixtures thereof; (d) 10 to 60 weight percent of one or more reinforcement agents; and (e) 0 to 50 weight percent of a polymeric toughener including a reactive functional group and/or a metal salt of a carboxylic acid; wherein 4 mm test bars prepared from said polyamide composition, exposed at a test temperature at 170° C. for a test period of 500 hours have a retention of tensile strength, on average, of at least 50 percent, as compared with that of unexposed control of identical composition and shape. Further disclosed is a molded or extruded thermoplastic article, including a thermoplastic polyamide composition, wherein 4 mm test bars of said thermoplastic polyamide composition, when exposed at 210° C. for a test period of 500 hours, have a retention of tensile strength of at least 70 percent.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. Provisional Application No. 61/137,345, filed on 30 Jul. 2008 and currently pending.

FIELD OF THE INVENTION

The present invention relates to the field of molded and extruded thermoplastic articles having improved long-term high temperature aging characteristics.

BACKGROUND OF INVENTION

High temperature resins based on polyamides possess desirable chemical resistance, processability and heat resistance. This makes them particularly well suited for demanding high performance automotive and electrical/electronics applications. There is a current and general desire in the automotive field to have high temperature resistant structures since temperatures higher than 150° C., even higher than 200° C., are often reached in underhood areas of automobiles. When plastic parts are exposed to such high temperatures for a prolonged period, such as in automotive under-the-hood applications or in electrical/electronics applications, the mechanical properties generally tend to decrease due to the thermo-oxidation of the polymer. This phenomenon is called heat aging.

In an attempt to improve heat aging characteristics, it has been the conventional practice to add heat stabilizers (also referred as antioxidants) to thermoplastic polyamide resins. Examples of such heat stabilizers include hindered phenol antioxidants, arrine antioxidants and phosphorus-based antioxidants. For polyamide compositions, three types of heat stabilizers are conventionally used to retain the mechanical properties of the composition upon exposure to high temperatures. One is the use of phenolic antioxidants optionally combined with a phosphorus based synergist as previously mentioned, the use of aromatic amines optionally combined with a phosphorus based synergist and the third one is the use of copper salts and derivatives. Phenolic antioxidants are known to improve the mechanical/physical properties of the thermoplastic composition up to an aging temperature of 120° C.

U.S. Pat. No. 5,965,652 discloses a thermally stable polyamide molding composition containing colloidal copper formed in situ. However, the disclosed compositions exhibit retention of impact strength only for a heat aging at 140° C.

GB patent 839,067 discloses a polyamide composition comprising a copper salt and a halide of a strong organic base. However, the disclosed compositions exhibit improved bending heat stability performance only for a heat aging at 170° C.

Existing technologies lead not only to a poor improvement of long-term heat aging resistance, but also the improved heat aging characteristics are insufficient for more demanding applications involving exposure to higher temperatures such as for example in automotive under-the-hood applications and in electrical/electronics applications.

US 2006/0155034 and US 2008/0146718 patent publications disclose polyamide compositions comprising a metal powder as thermal stabilizer with a fibrous reinforcing agent. Disclosed compositions exhibit improved mechanical properties such as tensile strength and elongation at break upon long-term heat aging at 215° C. However, such metal powders are not only expensive but they are also highly unstable because they are prone to spontaneous combustion.

EP 1041109 discloses a polyamide composition comprising a polyamide resin, a polyhydric alcohol having a melting point of 150 to 280° C., that has good fluidity and mechanical strength and is useful in injection welding techniques.

Unfortunately, with the existing technologies, molded articles based on polyamide or polyester compositions either suffer from an unacceptable deterioration of their mechanical properties upon long-term high temperature exposure or they are very expensive due to the use of high-cost heat stabilizers.

There remains a need for low-cost polyamide compositions that are suitable for manufacturing articles and that exhibit good mechanical properties after long-term high temperature exposure.

SUMMARY OF INVENTION

There is disclosed and claimed herein a molded or extruded thermoplastic article comprising a polyamide composition comprising

(a) a polyamide resin having a melting point and/or glass transition;

(b) 0.1 to 10 weight percent of one or more polyhydric alcohols having more than two hydroxyl groups and having a number average molecular weight (M_(n)) of less than 2000;

(c) 0.1 to 3 weight percent of one or more co-stabilizer(s) having a 10% weight loss temperature, as determined by thermogravimetric analysis, of greater than 30° C. below said melting point of said polyamide resin if said melting point is present, or at least 250° C. if said melting point is not present; selected from the group consisting of secondary aryl amines and hindered amine light stabilizers, and mixtures thereof;

(d) 10 to 60 weight percent of one or more reinforcement agents; and

(e) 0 to 50 weight percent of a polymeric toughener comprising a reactive functional group and/or a metal salt of a carboxylic acid;

wherein all weight percentages are based on the total weight of the polyamide composition; and wherein 4 mm test bars prepared from said polyamide composition, exposed at a test temperature at 170 ° C. for a test period of 500 hours, in an atmosphere of air, and tested according to ISO 527-2/1A, have a retention of tensile strength, on average, of at least 50 percent, as compared with that of an unexposed control of identical composition and shape

Further disclosed is a molded or extruded thermoplastic article, as disclosed above, wherein molded 4 mm test bars prepared from said polyamide composition, and exposed at a test temperature at 210° C. for a test period of 500 hours, in an atmosphere of air, and tested according to ISO 527-2/1A, have, on average, a retention of tensile strength of at least 50 percent, as compared with that of an unexposed control of identical composition and shape.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the description, unless otherwise specified, “high-temperature” means a temperature at or higher than 170° C., preferably at or higher than 210° C., and most preferably at or higher than 230° C.

In the present invention, unless otherwise specified, “long-term” refers to an exposure period equal or longer than 500 hrs, preferably equal or longer than 1000 hrs.

As used herein, the term “high heat stability”, as applied to the polyamide composition disclosed herein or to an article made from the composition, refers to the retention of physical properties (for instance, tensile strength) of 4 mm thick molded test bars consisting of the polyamide composition that are exposed to air oven aging (AOA) conditions at a test temperature at 170° C. for a test period of at least 500 h, in an atmosphere of air, and then tested according to ISO 527-2/1A method. The physical properties of the test bars are compared to that of unexposed controls that have identical composition and shape, and are expressed in terms of “% retention”. In another preferred embodiment the test temperature is at 210° C., the test period is at 500 hours and the exposed test bars have a % retention of tensile strength of at least 70%. Herein “high heat stability” means that said molded test bars, on average, meet or exceed a retention for tensile strength of 50% when exposed at a test temperature at 170° C. for a test period of at least 500 h. Compositions exhibiting a higher retention of physical properties for a given exposure temperature and time period have better heat stability.

The terms “at 170° C.” and “at 210° C.” refer to the nominal temperature of the environment to which the test bars are exposed; with the understanding that the actual temperature may vary by ±2° C. from the nominal test temperature.

The term “(meth)acrylate” is meant to include acrylate esters and methacrylate esters.

The polyamide resin used in the present invention has a melting point and/or glass transition. Herein melting points and glass transitions are as determined with differential scanning calorimetry (DSC) at a scan rate of 10° C./min in the first heating scan, wherein the melting point is taken at the maximum of the endothermic peak and the glass transition, if evident, is considered the mid-point of the change in enthalpy.

Polyamides are condensation products of one or more dicarboxylic acids and one or more diamines, and/or one or more aminocarboxylic acids, and/or ring-opening polymerization products of one or more cyclic lactams. Suitable cyclic lactams are caprolactam and laurolactam. Polyamides may be fully aliphatic or semi-aromatic.

Fully aliphatic polyamides used in the resin composition of the present invention are formed from aliphatic and alicyclic monomers such as diamines, dicarboxylic acids, lactams, aminocarboxylic acids, and their reactive equivalents. A suitable aminocarboxylic acid is 11-aminododecanoic acid. Suitable lactams are caprolactam and laurolactam. In the context of this invention, the term “fully aliphatic polyamide” also refers to copolymers derived from two or more such monomers and blends of two or more fully aliphatic polyamides. Linear, branched, and cyclic monomers may be used.

Carboxylic acid monomers comprised in the fully aliphatic polyamides include, but are not limited to aliphatic carboxylic acids, such as for example adipic acid (C6), pimelic acid (C7), sijberic acid (C8), azelaic acid (C9), decanedioic acid (C10), dodecanedioic acid (C12), tridecanedioic acid (C13), tetradecanedioic acid (C14), and pentadecanedioic acid (C15). Diamines can be chosen among diamines having four or more carbon atoms, including, but not limited to tetramethylene diamine, hexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine, 2-methylpentamethylene diamine, 2-ethyltetramethylene diamine, 2-methyloctamethylenediamine; trimethylhexamethylenediamine, meta-xylylene diamine, and/or mixtures thereof.

The semi-aromatic polyamide is a homopolymer, a copolymer, a terpolymer or more advanced polymers formed from monomers containing aromatic groups. One or more aromatic carboxylic acids may be terephthalate or a mixture of terephthalate with one or more other carboxylic acids, such as isophthalic acid, phthalic acid, 2-methyl terephthalic acid and naphthalic acid. In addition, the one or more aromatic carboxylic acids may be mixed with one or more aliphatic dicarboxylic acids, as disclosed above. Alternatively, an aromatic diamine such as meta-xylylene diamine (MXD) can be used to provide a semi-aromatic polyamide, an example of which is MXD6, a homopolymer comprising MXD and adipic acid.

Preferred polyamides disclosed herein are homopolymers or copolymers wherein the term copolymer refers to polyamides that have two or more amide and/or diamide molecular repeat units. The homopolymers and copolymers are identified by their respective repeat units. For copolymers disclosed herein, the repeat units are listed in decreasing order of mole % repeat units present in the copolymer. The following list exemplifies the abbreviations used to identify monomers and repeat units in the homopolymer and copolymer polyamides (PA):

-   HMD hexamethylene diamine (or 6 when used in combination with a     diacid) -   T Terephthalic acid -   M Adipic acid -   DMD Decamethylenediamine -   6     -Caprolactam -   DDA Decanedioic acid -   DDDA Dodecanedioic acid -   I Isophthalic acid -   MXD meta-xylylene diamine -   TMD 1,4-tetramethylene diamine -   4T polymer repeat unit formed from TMD and T -   6T polymer repeat unit formed from HMD and T -   DT polymer repeat unit formed from 2-MPMD and T -   MXD6 polymer repeat unit formed from MXD and AA -   66 polymer repeat unit formed from HMD and AA -   10T polymer repeat unit formed from DMD and T -   410 polymer repeat unit formed from TMD and DDA -   510 polymer repeat unit formed from 1,5-pentanediamine and DDA -   610 polymer repeat unit formed from HMD and DDA -   612 polymer repeat unit formed from HMD and DDDA -   6 polymer repeat unit formed from     -caprolactam p0 11 polymer repeat unit formed from     11-aminoundecanoic acid -   12 polymer repeat unit formed from 12-aminododecanoic acid

Note that in the art the term “6” when used alone designates a polymer repeat unit formed from

-caprolactam. Alternatively “6” when used in combination with a diacid such as T, for instance 6T, the “6” refers to HMD. In repeat units comprising a diamine and diacid, the diamine is designated first. Furthermore, when “6” is used in combination with a diamine, for instance 66, the first “6” refers to the diamine HMD, and the second “6” refers to adipic acid. Likewise, repeat units derived from other amino acids or lactams are designated as single numbers designating the number of carbon atoms.

In one embodiment the polyamide composition comprises a one or more polyamides selected from the group consisting of

Group (I) Polyamides having said melting point of less than 210° C., and comprising an aliphatic or semiaromatic polyamide selected from the group poly(pentamethylene decanediamide) (PA510), poly(pentamethylene dodecanediamide) (PA512), poly(ε-caprolactam/hexamethylene hexanediamide) (PA6/66), poly(ε-caprolactam/hexamethylene decanediamide) (PA6/610), poly(ε-caprolactam/hexamethylene dodecanediamide) (PA6/612), poly(hexamethylene tridecanediamide) (PA613), poly(hexamethylene pentadecanediamide) (PA615), poly(ε-caprolactam/tetramethylene terephthalamide) (PA6/4T), poly(ε-caprolactam/hexamethylene terephthalamide) (PA6/6T), poly(ε-caprolactam/decamethylene terephthalamide) (PA6/10T), poly(ε-caprolactam/dodecamethylene terephthalamide) (PA6/1 2T), poly(hexamethylene decanediamide/hexamethylene terephthalamide) (PA610/6T), poly(hexamethylene dodecanediamide/hexamethylene terephthalamide) (PA612/6T), poly(hexamethylene tetradecanediamide/hexamethylene terephthalamide) (PA614/6T), poly(ε-caprolactam/hexamethylene isophthalamide/hexamethylene terephthalamide) (PA6/61/6T), poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene decanediamide) (PA6/66/610), poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene dodecanediamide) (PA6166/612), poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene decanediamide/hexamethylene dodecanediamide) (PA6/66/610/612), poly(2-methylpentamethylene hexanediamide/hexamethylene hexanediamide/hexamethylene terephthamide) (PA D6/66//6T), poly(2-methylpentamethylene hexanediamide/hexamethylene hexanediamide/) (PA D6/66), poly(decamethylene decanediamide) (PA1010), poly(decamethylene dodecanediamide) (PA1012), poly(decamethylene decanediamide/decamethylene terephthalamide) (PA1010/10T) poly(decamethylene decanediamide/dodecamethylene decanediamide/decamethylene terephthalamide/dodecamethylene terephthalamide (PA1010/1210/10T/12T), poly(11-aminoundecanamide) (PA11), poly(11-aminoundecanamide/tetramethylene terephthalamide) (PA11/4T), poly(11-aminoundecanamide/hexamethylene terephthalamide) (PA11/6T), poly(11-aminoundecanamide/decamethylene terephthalamide) (PA11/10T), poly( 11-aminoundecanamide/dodecamethylene terephthalamide) (PA11/12T), poly(12-aminododecanamide) (PA12), poly(12-aminododecanamide/tetramethylene terephthalamide) (PA12/4T), poly(12-aminododecanamide/hexamethylene terephthalamide) (PA12/6T), poly(12-aminododecanamide/decamethylene terephthalamide) (PA12/10T) poly(dodecamethylene dodecanediamide) (PA1212), and poly(dodecamethylene dodecanediamide/dodecamethylene dodeca nediamide/dodecamethylene terephthalamide)) (PA1212/1 2T); Group (II) Polyamides having said melting point of at least 210 ° C., and comprising an aliphatic polyamide selected from the group consisting of poly(tetramethylene hexanediamide) (PA46), poly(ε-caprolactam) (PA 6), poly(hexamethylene hexanediamide/(ε-caprolactam/) (PA 66/6) poly(hexamethylene hexanediamide) (PA 66), poly(hexamethylene hexanediamide/hexamethylene decanediamide) (PA66/610), poly(hexamethylene hexanediamide/hexamethylene dodecanediamide) (PA66/612), poly(hexamethylene hexanediamide/decamethylene decanediamide) (PA66/1010), poly(hexamethylene decanediamide) (PA610), poly(hexamethylene dodecanediamide) (PA612), poly(hexamethylene tetradecanediamide) (PA614), poly(hexamethylene hexadecanediamide) (PA616), and poly(tetramethylene hexanediamide/2-methylpentamethylene hexanediamide) (PA46/D6);

Group (III) Polyamides having said melting point of at least 210° C., and comprising

(aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and         aliphatic diamines having 4 to 20 carbon atoms; and

(bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms         and said aliphatic diamine having 4 to 20 carbon atoms; and     -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon         atoms;

Group (IV) Polyamides comprising

(cc) about 50 to about 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and         aliphatic diamines having 4 to 20 carbon atoms; and

(dd) about 5 to about 50 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms         and said aliphatic diamine having 4 to 20 carbon atoms; and     -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon         atoms;

Group (V) Polyamides having said melting point of at least 260° C., and comprising

(ee) greater than 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and         aliphatic diamines having 4 to 20 carbon atoms; and

(ff) less than 5 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of:

-   -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms         and said aliphatic diamine having 4 to 20 carbon atoms;     -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon         atoms; and

Group (VI) Polyamides having no melting point selected from the group consisting of poly(hexamethylene isophthalamide/ hexamethylene terephthalamide) (61/6T) and poly(hexamethylene isophthalamide/hexamethylene terephthalamide/hexamethylene hexanediamide) (61/6T/66).

Group (I) Polyamides may have semiaromatic repeat units to the extent that the melting point is less than 210° C. and generally the semiaromatic polyamides of the group have less than 40 mole percent semiaromatic repeat units. Semiaromatic repeat units are defined as those derived from monomers selected from one or more of the group consisting of: aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms. Another embodiment is a molded or extruded thermoplastic article wherein said polyamide resin is selected from Group (III) Polyamides selected from the group consisting of poly(tetramethylene hexanediamide/tetramethylene terephthalamide) (PA46/4T), poly(tetramethylene hexanediamide/hexamethylene terephthalamide) (PA46/6T), poly(tetramethylene hexanediamide/2-methylpentamethylene hexanediamide/decamethylene terephthalamide) PA46/D6/10T), poly(hexamethylene hexanediamide/hexamethylene terephthalamide) (PA66/6T), poly(hexamethylene hexanediamide/hexamethylene isophthalamide/hexamethylene terephthalamide PA66/61/6T, and poly(hexamethylene hexanediamide/2-methylpentamethylene hexanediamide/hexamethylene terephthalamide (PA66/D6/6T); and a most preferred Group (III) polyamide is PA 66/6T.

Another embodiment is a molded or extruded thermoplastic article wherein said polyamide resin is selected from Group (IV) Polyamides selected from the group consisting of poly(tetramethylene terephthalamide/hexamethylene hexanediamide) (PA4T/66), poly(tetramethylene terephthalamide/ε-caprolactam) (PA4T/6), poly(tetramethylene terephthalamide/hexamethylene dodecanediamide) (PA4T/612), poly(tetramethylene terephthalamide/2-methylpentamethylene hexanediamide/hexamethylene hexanediamide) (PA4T/D6/66), poly(hexaamethylene terephthalamide/2-methylpentamethylene terephthalamide/hexamethylene hexanediamide) (PA6T/DT/66), poly(hexamethylene terephthalamide/hexamethylene hexanediamide) PA6T/66, poly(hexaamethylene terephthalamide /hexamethylene decanediamide) (PA6T/610), poly(hexamethylene terephthalamide/hexamethylene tetradecanediamide) (PA6T/614), poly(nonamethylene terephthalamide/nonamethylene decanediamide) (PA9T/910), poly(nonamethylene terephthalamide/nonamethylene dodecanediamide) (PA9T/912), poly(nonamethylene terephthalamide/11-aminoundecanamide) (PA9T/11), poly(nonamethylene terephthalamide/12-aminododecanamide) (PA9T/12), poly(decamethylene terephthalamide/11-aminoundecanamide) (PA 10T/11), poly(decamethylene terephthalamide/12-aminododecanamide) (PA10T/12) poly(decamethylene terephthalamide/decamethylene decanediamide) (PA110T/1010), poly(decamethylene terephthalamide/decamethylene dodecanediamide) (PA10T/1012), poly(decamethylene terephthalamide/tetramethylene hexanediamide) (PA10T/46), poly(decamethylene terephthalamide/ε-caprolactam) (PA10T/6), poly(decamethylene terephthalamide/hexamethylene hexanediamide) (PA10T/66), poly(dodecamethylene terephthalamide/dodecamethylene dodecanediamide) (PA12T/1212), poly(dodecamethylene terephthalamide/ε-caprolactam) (PA12T/6), and poly(dodecamethylene terephthalamide/hexamethylene hexanediamide) (PA12T/66); and a most preferred Group (IV) polyamide is PA6T/66.

Another embodiment is a molded or extruded thermoplastic article wherein said polyamide resin is selected from Group (V) Polyamides selected from the group consisting of poly(tetramethylene terephthalamide/2-methylpentamethylene terephthalamide) PA4T/DT, poly(tetramethylene terephthalamide/hexamethylene terephthalamide) PA4T/6T, poly(tetramethylene terephthalamide/decamethylene terephthalamide) PA4T/10T, poly(tetramethylene terephthalamide/dodecamethylene terephthalamide)PA4T/12T, poly(tetramethylene terephthalamide/2-methylpentamethylene terephthalamide/hexamethylene terephthalamide) (PA4T/DT/6T), poly(tetramethylene terephthalamide/hexamethylene terephthalamide/2-methylpentamethylene terephthalamide) (PA4T/6T/DT), poly(hexamethylene terephthalamide/2-methylpentamethylene terephthalamide) (PA6T/DT), poly(hexamethylene hexanediamide/hexamethylene isophthalamide) (PA 6T/61), poly(hexamethylene terephthalamide/decamethylene terephthalamide) PA6T/10T, poly(hexamethylene terephthalamide/dodecamethylene terephthalamide) (PA6T/12T), poly(hexamethylene terephthalamide/2-methylpentamethylene terephthalamide/poly(decamethylene terephthalamide) (PA6T/DT/10T), poly(hexamethylene terephthalamide/decamethylene terephthalamide/dodecamethylene terephthalamide) (PA6T/10T/12T), poly(decamethylene terephthalamide) (PA10T), poly(decamethylene terephthalamide/tetramethylene terephthalamide) (PA10T/4T), poly(decamethylene terephthalamide/2-methylpentamethylene terephthalamide) (PA110T/DT), poly(decamethylene terephthalamide/dodecamethylene terephthalamide) (PA10T/12T), poly(decamethylene terephthalamide/2-methylpentamethylene terephthalamide/(decamethylene terephthalamide) (PA10T/DT/12T). poly(dodecamethylene terephthalamide) (PA12T), poly(dodecamethylene terephthalamide)/tetramethylene terephthalamide) (PA12T/4T), poly(dodecamethylene terephthalamide)/hexamethylene terephthalamide) PA12T/6T, poly(dodecamethylene terephthalamide)/decamethylene terephthalamide) (PA12T/10T), and poly(dodecamethylene terephthalamide)/2-methylpentamethylene terephthalamide) (PA12T/DT); and a most preferred Group (V) polyamide is PA6T/DT.

In various embodiments the polyamide is a Group (I) Polyamide, Group (II) Polyamide, Group (III) Polyamide, Group (IV) Polyamide, Group (V) Polyamide or Group (VI) Polyamide, respectively.

The polyamides may also be blends of two or more polyamides. Preferred blends include those selected from the group consisting of Group (I) and Group (II) Polyamides; Group (I) and Group (III) Polyamide, Group (I) and Group (VI) Polyamides, Group (II) and Group (III) Polyamides, Group (II) and Group (IV) Polyamides, Group (II) and Group (V) Polyamides, Group (II) and Group (VI) Polyamides, Group (III) and Group (VI) Polyamides, and Group (IV) and Group (V) Polyamides.

A preferred blend includes Group (II) and Group (V) Polyamides, and a specific preferred blend includes poly(hexamethylene hexanediamide) (PA 66) and poly(hexamethylene terephthalamide/2-methylpentamethylene terephthalamide) (PA 6T/DT).

Another preferred blend includes Group (II) and Group (III) Polyamides and a specific preferred blend includes poly(ε-caprolactam) (PA6) and poly(hexamethylene hexanediamide/hexamethylene terephthalamide (PA66/6T).

Another embodiment is a molded or extruded thermoplastic article comprising a thermoplastic polyamide composition as disclosed above, wherein molded 4 mm test bars prepared from said polyamide composition, and exposed at a test temperature at 210° C. for a test period of 500 hours, in an atmosphere of air, and tested according to ISO 527-2/1A, have, on average, a retention of tensile strength of at least 50 percent, as compared with that of an unexposed control of identical composition and shape. Thermoplastic polyamide compositions meeting these test requirements are referred to as “meeting the requirements of AOA 210° C./500 hours testing.”

The thermoplastic polyamide compositions meeting the requirements of AOA 210° C./500 hours testing comprise one or more polyamide resins wherein said polyamide resin comprises a one or more polyamides independently selected from the groups consisting of Group (II) polyamides, Group (III) polyamides, Group (IV) polyarrides, Group (V) polyamides and Group (VI) polyamides, as disclosed above.

In various embodiments thermoplastic polyamide compositions meeting the requirements of AOA 210° C./500 hours are Group (II) polyamides, Group (III) Polyamides, Group (IV) Polyarnides, Group (V) Polyamides and Group (VI) Polyamides, respectively.

A further preferred embodiment is the molded or extruded thermoplastic article wherein said polyamide resin is selected from Group (IV) Polyamides and wherein said test temperature is at least 210° C. for a test period of at least 500 hours and said retention of tensile strength is at least 70%, and more preferably at least 80% and 90%.

A further preferred embodiment is the molded or extruded thermoplastic article wherein said polyamide resin is selected from Group (V) Polyamides and wherein said test temperature is at least 230° C. for a test period of at least 500 hours and said retention of tensile strength is at least 60%, and more preferably at least 70%, 80% and 90%.

The molded or extruded thermoplastic article comprises 0.25 to 15 weight percent of one or more polyhydric alcohols having more than two hydroxyl groups and having a number average molecular weight (M_(n)) of less than 2000 of less than 2000 as determined for polymeric materials with gel permeation chromatography (GPC)

Polyhydric alcohols may be selected from aliphatic hydroxylic compounds containing more than two hydroxyl groups, aliphatic-cycloaliphatic compounds containing more than two hydroxyl groups, cycloaliphatic compounds containing more than two hydroxyl groups, aromatic and saccharides.

An aliphatic chain in the polyhydric alcohol can include not only carbon atoms but also one or more hetero atoms which may be selected, for example, from nitrogen, oxygen and sulphur atoms. A cycloaliphatic ring present in the polyhydric alcohol can be monocyclic or part of a bicyclic or polycyclic ring system and may be carbocyclic or heterocyclic. A heterocyclic ring present in the polyhydric alcohol can be monocyclic or part of a bicyclic or polycyclic ring system and may include one or more hetero atoms which may be selected, for example, from nitrogen, oxygen and sulphur atoms. The one or more polyhydric alcohols may contain one or more substituents, such as ether, carboxylic acid, carboxylic acid amide or carboxylic acid ester groups.

Examples of polyhydric alcohol containing more than two hydroxyl groups include, without limitation, triols, such as glycerol, trimethylolpropane, 2,3-di-(2′-hydroxyethyl)-cyclohexan-1-ol, hexane-1,2,6-triol, 1,1,1-tris-(hydroxymethyl)ethane, 3-(2′-hydroxyethoxy)-propane-1,2-diol, 3-(2′-hydroxypropoxy)-propane-1,2-diol, 2-(2′-hydroxyethoxy)-hexane-1,2-diol, 6-(2′-hydroxypropoxy)-hexane-1,2-diol, 1,1,1-tris-[(2′-hydroxyethoxy)-methyl]-ethane, 1,1,1-tris-[(2′-hydroxypropoxy)-methyl]-propane, 1,1,1-tris-(4′-hydroxyphenyl)-ethane, 1,1,1-tris-(hydroxyphenyl)-propane, 1,1,3-tris-(dihydroxy-3-methylphenyl)-propane, 1,1,4-tris-(dihydroxyphenyl)-butane, 1,1,5-tris-(hydroxyphenyl)-3-methylpentane, di-trimethylopropane, trimethylolpropane ethoxylates, or trimethylolpropane propoxylates; polyols such as pentaerythritol, dipentaerythritol, and tripentaerythritol; and saccharides, such as cyclodextrin, D-mannose, glucose, galactose, sucrose, fructose, xylose, arabinose, D-mannitol, D-sorbitol, D-or L-arabitol, xylitol, iditol, talitol, allitol, altritol, guilitol, erythritol, threitol, and D-gulonic-y-lactone; and the like.

Preferred polyhydric alcohols include those having a pair of hydroxyl groups which are attached to respective carbon atoms which are separated one from another by at least one atom. Especially preferred polyhydric alcohols are those in which a pair of hydroxyl groups is attached to respective carbon atoms which are separated one from another by a single carbon atom.

Preferably, the polyhydric alcohol used in the thermoplastic composition is pentaerythritol, dipentaerythritol, tripentaerythritol, di-trimethylolpropane, D-mannitol, D-sorbitol and xylitol. More preferably, the polyhydric alcohol used is dipentaerythritol and/or tripentaerythritol. A most preferred polyhydric alcohol is dipentaerythritol.

In various embodiments the content of said polyhydric alcohol in the thermoplastic composition is 0.25 to 15 weight percent, preferably 0.25 to 8 weight percent, and more preferably 0.25 to 5, and 1 to 4 weight percent.

The polyamide composition comprises 0.1 to 3 weight percent of one or more co-stabilizer(s) having a 10% weight loss temperature, as determined by thermogravimetric analysis (TGA), of greater than 30 degrees below the melting point of the polyamide resin, if a melting point is present, or at least 250° C. if said melting point is not present, selected from the group consisting of secondary aryl amines and hindered amine light stabilizers (HALS), and mixtures thereof. For the purposes of this invention, TGA weight loss will be determined according to ASTM D 3850-94, using a heating rate of 10° C./min, in air purge stream, with an appropriate flow rate of 0.8 mL/second. The co-stabilizer preferably has a 10% weight loss temperature, as determined by TGA, of at least 270° C., and more preferably 290° C., 320° C., and 340° C., and most preferably at least 350° C. The one or more co-stabilizers preferably are present from at or about 0.1 to at or about 1 weight percent, or more preferably from at or about 0.1 to at or about 0.7 weight percent, based on the total weight of the polyamide composition.

Secondary aryl amines useful in the invention are high molecular weight organic compound having low volatility. Preferably, the high molecular weight organic compound will be selected from the group consisting of secondary aryl amines further characterized as having a molecular weight of at least 260 g/mol and preferably at least 350 g/mol, together with a 10% weight loss temperature as determined by thermogravimetric analysis (TGA) of at least 290° C., preferably at least 300° C., 320° C., 340° C., and most preferably at least 350° C.

By secondary aryl amine is meant an amine compound that contains two carbon radicals chemically bound to a nitrogen atom where at least one, and preferably both carbon radicals, are aromatic. Preferably, at least one of the aromatic radicals, such as, for example, a phenyl, naphthyl or heteroaromatic group, is substituted with at least one substituent, preferably containing 1 to about 20 carbon atoms.

Examples of suitable secondary aryl amines include 4,4′di(α,α-dimethylbenzyl)diphenylamine available commercially as Naugard 445 from Uniroyal Chemical Company, Middlebury, Conn.; the secondary aryl amine condensation product of the reaction of diphenylamine with acetone, available commercially as Aminox from Uniroyal Chemical Company; and para-(paratoluenesulfonylamido) diphenylamine also available from Uniroyal Chemical Company as Naugard SA. Other suitable secondary aryl amines include N,N′-di-(2-naphthyl)-p-phenylenediamine, available from ICI Rubber Chemicals, Calcutta, India. Other suitable secondary aryl amines include 4,4′-bis(α,α′-tertiaryoctyl)diphenylamine, 4,4′-bis(a-methylbenzhydryl)diphenylamine, and others from EP 0509282 B1.

The hindered amine light stabilizers (HALS) may be one or more hindered amine type light stabilizers (HALS).

HALS are compounds of the following general formulas and combinations thereof:

In these formulas, R₁ up to and including R₅ are independent substituents. Examples of suitable substituents are hydrogen, ether groups, ester groups, amine groups, amide groups, alkyl groups, alkenyl groups, alkynyl groups, aralkyl groups, cycloalkyl groups and aryl groups, in which the substituents in turn may contain functional groups; examples of functional groups are alcohols, ketones, anhydrides, imines, siloxanes, ethers, carboxyl groups, aldehydes, esters, amides, imides, amines, nitriles, ethers, urethanes and any combination thereof. A hindered amine light stabilizer may also form part of a polymer or oligomer.

Preferably, the HALS is a compound derived from a substituted piperidine compound, in particular any compound derived from an alkyl-substituted piperidyl, piperidinyl or piperazinone compound, and substituted alkoxypiperidinyl compounds. Examples of such compounds are: 2,2,6,6-tetramethyl-4-piperidone; 2,2,6,6-tetrametyl-4-piperidinol; bis-(1,2,2,6,6-pentamethyl piperidyl)-(3′,5′-di-tert-butyl-4′-hydroxybenzyl)butylmalonate; di-(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770, MW 481); oligomer of N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol and succinic acid (Tinuvin® 622); oligomer of cyanuric acid and N,N-di(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene diamine; bis-(2,2,6,6-tetramethyl-4-piperidinyl) succinate; bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinijvin® 123); bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (Tinuvin® 765); Tinuvin® 144; Tinuvin® XT850; tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate; N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexane-1,6-diamine (Chimasorb® T5); N-butyl-2,2,6,6-tetramethyl-4-piperidinamine; 2,2′-[(2,2,6,6-tetramethyl-piperidinyl)-imino]-bis-[ethanol]; poly((6-morpholine-S-triazine-2,4-diyl)(2,2,6,6-tetramethyl-4-piperidinyl)-iminohexamethylene-(2,2,6,6-tetramethyl-4-piperidinyl)-imino) (Cyasorb® UV 3346); 5-(2,2,6,6-tetramethyl-4-piperidinyl)-2-cyclo-undecyl-oxazole) (Hostavin® N20); 1,1′-(1,2-ethane-di-yl)-bis-(3,3′,5,5′-tetramethyl-piperazinone); 8-acetyl-3-dothecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro(4,5)decane-2,4-dione; polymethylpropyl-3-oxy-[4(2,2,6,6-tetramethyl)-piperidinyl]siloxane (Uvasil® 299); 1,2,3,4-butane-tetracarboxylic acid-1,2,3-tris(1,2,2,6,6-pentamethyl-4-piperidinyl)-4-tridecylester; copolymer of alpha-methylstyrene-N-(2,2,6,6-tetramethyl-4-piperidinyl) maleimide and N-stearyl maleimide; 1,2,3,4-butanetetracarboxylic acid, polymer with beta,beta,beta′,beta′-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, 1,2,2,6,6-pentamethyl-4-piperidinyl ester (Mark® LA63); 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol,beta,beta,beta′,beta′-tetramethyl-polymer with 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinyl ester (Mark® LA68); D-glucitol, 1,3:2,4-bis-O-(2,2,6,6-tetramethyl-4-piperidinylidene)-(HALS 7); oligomer of 7-oxa-3,20-diazadispiro[5.1.11.2]-heneicosan-21-one-2,2,4,4-tetramethyl-20-(oxiranylmethyl) (Hostavin® N30); propanedioic acid, [(4-methoxyphenyl)methylene]-,bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester (Sanduvor® PR 31); formamide, N,N′-1,6-hexanediylbis[N-(2,2,6,6-tetramethyl-4-piperidinyl (Uvinul® 4050H); 1,3,5-triazine-2,4,6-triamine, N,N′″-[1,2-ethanediylbis [[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]]-bis[N′, N″-dibutyl-N′,N″-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) (Chimassorb® 119 MW 2286); poly[[6-[(1,1,3,33-tetramethylbutyl) amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-peperidinyl)-imino]-1,6-hexanediyl [(2,2,6,6-tetramethyl-4-piperidinyl)imino]] (Chimassorb® 944 MW 2000-3000); 1,5-dioxaspiro (5,5)undecane 3,3-dicarboxylic acid, bis(2,2,6,6-tetramethyl-4-peridinyl)ester (Cyasorb® UV-500); 1,5-dioxaspiro (5,5) undecane 3,3-dicarboxylic acid, bis (1,2,2,6,6-pentamethyl-4-peridinyl)ester (Cyasorb® UV-516); N-2,2,6,6-tetramethyl-4-piperidinyl-N-amino-oxamide; 4-acryloyloxy-1,2,2,6,6-pentamethyl-4-piperidine. 1,5,8,12-tetrakis[2′,4′-bis(1″,2″,2″,6″,6″-pentamethyl-4″-piperidinyl(butyl)amino)-1′,3′,5′-triazine-6′-yl]-1,5,8,12-tetraazadodecane; HALS PB-41 (Clariant Huningue S. A.); Nylostab® S-EED (Clariant Huningue S. A.); 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)-pyrrolidin-2,5-dione; Uvasorb® HA88; 1,1′-(1,2-ethane-di-yl)-bis-(3,3′,5,5′-tetra-methyl-piperazinone) (Good-rite® 3034); 1,1′1″-(1,3,5-triazine-2,4,6-triyltris ((cyclohexylimino)-2,1-ethanediyl)tris(3,3,5,5-tetramethylpiperazinone) (Good-rite® 3150) and; 1,1′,1″-(1,3,5-triazine-2,4,6-triyltris((cyclohexylimino)-2,1-ethanediyl)tris(3,3,4,5,5-tetramethylpiperazinone) (Good-rite® 3159). (Tinuvin® and Chimassorb® materials are available from Ciba Specialty Chemicals; Cyasorb® materials are available from Cytec Technology Corp.; Uvasil® materials are available from Great Lakes Chemical Corp.; Saduvor®, Hostavin®, and Nylostab® materials are available from Clariant Corp.; Uvinul® materials are available from BASF; Uvasorb® materials are available from Partecipazioni Industriali; and Good-rite® materials are available from B.F. Goodrich Co. Mark® materials are available from Asahi Denka Co.)

Preferred HALS include high-molecular weight oligomeric or polymeric HALS having a molecular weight of more than about 1000, and preferably more than about 2000.

Other specific HALS are selected from the group consisting or di-(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770, MW 481) Nylostab® S-EED (Clariant Huningue S. A.); 1,3,5-triazine-2,4,6-triamine, N,N′″-[1,2-ethanediylbis [[[4,6-bis[butyl(1,2,2,6,6-pentamethyl4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]]-bis[N′,N″-dibutyl-N′,N″-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) (Chimassorb® 119 MW 2286); and poly[[6-[(1,1,3,33-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-peperidinyl)-imino]-1,6-hexanediyl [(2,2,6,6-tetramethyl-4-piperidinyl)imino]] (Chimassorb® 944 MW 2000-3000).

Mixtures of secondary aryl amines and HALS may be used. A preferred embodiment comprises at least two co-stabilizers, at least one selected from the secondary aryl amines; and at least one selected from the group of HALS, as disclosed above, wherein the total weight percent of the mixture of co-stabilizers is at least 0.5 wt percent, and preferably at least 0.9 weight percent. The molded or extruded thermoplastic article comprises 10 to about 60 weight percent, and preferably about 12.5 to 55 weight percent and 15 to 50 weight percent, of one or more reinforcement agents. The reinforcement agent may be any filler, but is preferably selected from the group consisting calcium carbonate, glass fibers with circular and noncircular cross-section, glass flakes, glass beads, carbon fibers, talc, mica, wollastonite, calcined clay, kaolin, diatomite, magnesium sulfate, magnesium silicate, barium sulfate, titanium dioxide, sodium aluminum carbonate, barium ferrite, potassium titanate and mixtures thereof.

Glass fibers with noncircular cross-section refer to glass fiber having a cross section having a major axis lying perpendicular to a longitudinal direction of the glass fiber and corresponding to the longest linear distance in the cross section. The non-circular cross section has a minor axis corresponding to the longest linear distance in the cross section in a direction perpendicular to the major axis. The non-circular cross section of the fiber may have a variety of shapes including a cocoon-type (figure-eight) shape, a rectangular shape; an elliptical shape; a roughly triangular shape; a polygonal shape; and an oblong shape. As will be understood by those skilled in the art, the cross section may have other shapes. The ratio of the length of the major axis to that of the minor access is preferably between about 1.5:1 and about 6:1. The ratio is more preferably between about 2:1 and 5:1 and yet more preferably between about 3:1 to about 4:1. Suitable glass fiber are disclosed in EP 0 190 001 and EP 0 196 194.

The molded or extruded thermoplastic article, optionally, comprises 0 to 50 weight percent of a polymeric toughener comprising a reactive functional group and/or a metal salt of a carboxylic acid. In one embodiment the molded or extruded thermoplastic article comprises 2 to 20 weight percent polymeric toughener selected from the group consisting of: a copolymer of ethylene, glycidyl (meth)acrylate, and optionally one or more (meth)acrylate esters; an ethylene/a-olefin or ethylene/a-olefin/diene copolymer grafted with an unsaturated carboxylic anhydride; a copolymer of ethylene, 2-isocyanatoethyl (meth)acrylate, and optionally one or more (meth)acrylate esters; and a copolymer of ethylene and acrylic acid reacted with a Zn, Li, Mg or Mn compound to form the corresponding ionomer.

In the present invention, the polyamide composition may also comprise other additives commonly used in the art, such other heat stabilizers or antioxidants, antistatic agents, blowing agents, lubricants, plasticizers, and colorant and pigments.

Other heat stabilizers include copper stabilizers and hindered phenols, and mixtures thereof.

A significant advantage of the molded or extruded thermoplastic articles of the invention is that high thermal stability is provided without the use of conventional copper heat stabilizers. Copper heat stabilizers tend to act as corrosive agents over long periods of time at elevated temperatures; and in some environments actually cause degradation of semiaromatic polymers. Thus, another embodiment is molded or extruded thermoplastic article wherein said polyamide composition comprises less than 25 ppm copper as determined with atomic absorption spectroscopy.

Herein the polyamide composition is a mixture by melt-blending, in which all polymeric ingredients are adequately mixed, and all non-polymeric ingredients are adequately dispersed in a polymer matrix. Any melt-blending method may be used for mixing polymeric ingredients and non-polymeric ingredients of the present invention. For example, polymeric ingredients and non-polymeric ingredients may be fed into a melt mixer, such as single screw extruder or twin screw extrjder, agitator, single screw or twin screw kneader, or Banbury mixer, and the addition step may be addition of all ingredients at once or gradual addition in batches. When the polymeric ingredient and non-polymeric ingredient are gradually added in batches, a part of the polymeric ingredients and/or non-polymeric ingredients is first added, and then is melt-mixed with the remaining polymeric ingredients and non-polymeric ingredients that are subsequently added, until an adequately mixed composition is obtained. If a reinforcing filler presents a long physical shape (for example, a long glass fiber), drawing extrusion molding may be used to prepare a reinforced composition.

The polyamide composition having a polyhydroxy polymer, as disclosed above, is useful in increasing long-term heat stability at high temperatures of molded or extruded articles made therefrom. The long-term heat stability of the articles can be assessed by exposure (air oven ageing) of 4 mm thick test samples at various test temperatures in an oven for various test periods of time. The oven test temperatures for the composition disclosed herein include 170° C. and 500 hours test periods; 210° C. and 500 hours test periods; and 230° C. and 500 hours test periods. The test samples, after air oven ageing, are tested for tensile strength and elongation to break, according to ISO 527-2/1A test method; and compared with unexposed controls having identical composition and shape, that are dry as molded (DAM). The comparison with the DAM controls provides the retention of tensile strength and/or retention of elongation to break, and thus the various compositions can be assessed as to long-term heat stability performance.

In various embodiments the thermoplastic polyamide composition has an AOA 170° C./500 hours retention of tensile strength of at least 50% and preferably at least 60, 70, 80, and 90%, based upon comparison with DAM non-exposed controls.

In various embodiments the thermoplastic polyamide composition has an AOA 210° C./500 hours retention of tensile strength of at least 50% and preferably at least 70, 80, and 90%, based upon comparison with DAM non-exposed controls.

In another aspect, the present invention relates a use of the above disclosed polyamide compositions for high temperature applications.

In another aspect, the present invention relates to a method for manufacturing an article by shaping the thermoplastic corriposition of the invention. Examples of articles are films or laminates, automotive parts or engine parts or electrical/electronics parts. By “shaping”, it is meant any shaping technique, such as for example extrusion, injection moulding, thermoform moulding, compression moulding or blow moulding. Preferably, the article is shaped by injection moulding or blow moulding.

The molded or extruded thermoplastic articles disclosed herein may have application in many vehicular components that meet one or more of the following requirements: high impact requirements; significant weight reduction (over conventional metals, for instance); resistance to high temperature; resistance to oil environment; resistance to chemical agents such as coolants; and noise reduction allowing more compact and integrated design. Specific molded or extruded thermoplastic articles are selected from the group consisting of charge air coolers (CAC); cylinder head covers (CHC); oil pans; engine cooling systems, including thermostat and heater housings and coolant pumps; exhaust systems including mufflers and housings for catalytic converters; air intake manifolds (AIM); and timing chain belt front covers. As an illustrative example of desired mechanical resistance against long-term high temperature exposure, a charge air cooler can be mentioned. A charge air cooler is a part of the radiator of a vehicle that improves engine combustion efficiency. Charge air coolers reduce the charge air temperature and increase the density of the air after compression in the turbocharger thus allowing more air to enter into the cylinders to improve engine efficiency. Since the temperature of the incoming air can be more than 200° C. when it enters the charge air cooler, it is required that this part be made out of a composition maintaining good mechanical properties under high temperatures for an extended period of time.

The present invention is further illustrated by the following examples. It should be understood that the following examples are for illustration purposes only, and are not used to limit the present invention thereto.

EXAMPLES Methods

Compounding Method

All Examples and Comparative Examples were prepared by melt blending the ingredients listed in the Tables in a 30 mm twin screw extruder (ZSK 30 by Coperion) operating at about 310° C. barrel setting using a screw speed of about 300 rpm, a throughput of 13.6 kg/hour and a melt temperature measured by hand of about 355° C. The glass fibers were added to the melt through a screw side feeder. Ingredient quantities shown in the Tables are given in weight percent on the basis of the total weight of the thermoplastic composition.

The compounded mixture was extruded in the form of laces or strands, cooled in a water bath, chopped into granules and placed into sealed aluminum lined bags in order to prevent moisture pick up. The cooling and cutting conditions were adjusted to ensure that the materials were kept below 0.15 wt % of moisture level.

Physical Properties Measurement

Mechanical tensile properties, i.e. E-modulus, stress at break (Tensile strength) and strain at break (elongation at break) were measured according to ISO 527-2/1A. Measurements were made on injection molded ISO tensile bars. Mold temperature for PA 6T/DT test specimens was 145-150° C.; mold temperature for PA 6T/66 test specimens was 90-100° C.; and melt temperature was 325-330° C. for both resins.

The thickness of the test specimens was 4 mm and a width of 10 mm according to ISO 527/1A at a testing speed of 5 mm/min (tensile strength and elongation). Tensile Modulus was measured at 1 mm/min.

Air Oven Ageing (AOA)

The test specimens were heat aged in a re-circulating air ovens (Heraeus type UT6060) according to the procedure detailed in ISO 2578. At various heat aging times, the test specimens were removed from the oven, allowed to cool to room temperature and sealed into aluminum lined bags until ready for testing. The tensile mechanical properties were then measured according to ISO 527 using a Zwick tensile instrument. The average values obtained from 5 specimens are given in the Tables.

Retention of tensile strength (TS) and elongation at break (EL) corresponds to the percentage of the tensile strength and elongation at break after heat aging for 500 hours 1000 hours in comparison with the value of specimens non-heat-aged control specimens considered as being 100%.

Materials

PA 6T/66 refers HTN502 NC010, a copolyamide made from terephthalic acid, adipic acid, and hexamethylenediamine; wherein the two acids are used in a 55:45 molar ratio; having a melting point of ca. 310° C., having an inherent viscosity (IV), according to ASTM D2857 method, in the range of 0.9 to 1.0 (typically 0.96) available from E.I. DuPont de Nemours and Company, Wilmington, Del., USA.

PA6T/DT refers HTN501 NC010, a copolyamide of terephthalic acid, hexamethylenediamine, and 2-methyl-pentamethylenediamine having an inherent viscosity (IV), according to ASTM D2857 method, in the range of 0.8 to 0.95 (typically 0.88) and a melting point of about 300° C., and available from E.I. DuPont de Nemours and Company, Wilmington, Del., USA.

DPE refers to dipentaerythritol that was from Perstorp Speciality Chemicals AB, Perstorp, Sweden as Di-Penta 93.

TPE refers to tripentaerythritol that was from Sigma Aldrich Co., Milwaukee Wis.

Glass Fiber D refers to PPG 3540 chopped glass fiber available fro PPG Industries, Pittsburgh, Pa.

Naugard® 445 hindered amine refers to 4,4′di(.α,α-dimethylbenzyl)diphenylamine available commercially from Uniroyal Chemical Company, Middlebury, Conn.

Irganox® 1010 stabilizer was available from Ciba Speciality Chemicals Inc, Switzerland.

Irganox® 1098 stabilizer was available from Ciba Speciality Chemicals Inc, Switzerland.

Chimassorb® 944 refers to (poly[[6-[(1,1,3,3-tetramethylbutyl) amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)-imino]-1,6-hexanediyl [(2,2,6,6-tetramethyl-4-piperidinyl)imino]]), supplied by Ciba Specialty Chemicals.

Chimassorb® 119 is (1,3,5-triazine-2,4,6-triamine, N,N′″-[1,2-ethanediylbis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]]-bis[N′, N″-dibutyl-N′,N″-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)), supplied by Ciba Specialty Chemicals.

Wax OP is a lubricant manufactured by Clariant Corp., Charlotte, N.C.

Black Pigment B refers to 25 wt % carbon black in PA6 polymer.

Example 1 and C-1- C-5

Compositions of Examples 1 and Comparative Examples C-1-C-5 are listed in Table 1 for PA6T/DT compositions. Tensile properties after AOA at 210° C/ and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 1. Higher values of tensile strength (TS) mean better mechanical properties. Higher % retention of tensile strength indicate a higher thermal stability.

Data in Table 1 indicates that Example 1 having 1.5 wt % DPE and 1 wt % Naugard® 445 hindered amine has higher % retention of tensile strength than the Comparative Examples containing Naugard alone; copper heat stabilizer alone; 1.5 wt % DPE alone; or Naugard® 445 hindered amine alone. Example 1 shows surprising and unexpected results, indicated by the much higher % retention of tensile strength under AOA at 230° C./1000 hours, as compared to conventional copper stabilizer commonly used in commercial products.

Example 2 and C-6- C-10

Compositions of Examples 2 and Comparative Examples C-6-C-10 are listed in Table 2 for PA6T/DT compositions. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 2

Data in Table 2 indicates that Examples 2 having 2 wt % TPE, 0.5 wt % Naugard® 445 hindered amine, and 0.5 wt % Chimassorb® 944FDL has higher % retention of tensile strength than the Comparative Examples containing 2.0 wt % TPE alone; Chimassorb® 944FDL; or Naugard® 445 hindered amine alone.

TABLE 1 Example C-1 C-2 C-3 C-4 C-5 1 PA6T/DT 64.75 64.05 63.25 61.75 63.75 62.25 DPE 1.5 3 1.5 Cu heat stabilizer 0.7 Naugard 445 1 1 Wax OP 0.25 0.25 0.25 0.25 0.25 0.25 Glass Fiber D 35 35 35 35 35 35 AOA 210° C. TS (MPa) 0 h 225 223 214 212 214 219 TS (MPa) 500 h 115 141 218 218 150 220 TS (MPa) 1000 h 98 130 210 208 133 207  500 hrs TS Retention (%) 51 63 102 103 70 100 1000 hrs TS Retention (%) 44 58 98 98 62 95 EI (%) 0 h 2.3 2.4 2.2 2.2 2.2 2.2 EI (%) 500 h 1.2 1.4 2.2 2.2 1.5 2.2 EI (%) 1000 h 0.9 1.3 2.1 2.1 1.3 2.1  500 hrs EI Retention (%) 52 58 100 100 68 100 1000 hrs EI Retention (%) 39 54 95 95 59 95 AOA 230° C. TS (MPa) 0 h 225 223 214 212 214 219 TS (MPa) 500 h 75 125 135 172 112 165 TS (MPa) 1000 h 20 91 115 156 52 141 500 hrs TS Retention (%) 33 56 63 81 52 75 1000 hrs TS Retention (%) 9 41 54 74 24 64 EI (%) 0 h 2.3 2.4 2.2 2.2 2.2 2.2 EI (%) 500 h 0.8 1.1 1.3 1.8 1.2 1.7 EI (%) 1000 h 0.3 0.8 1.2 1.7 0.4 1.4  500 hrs EI Retention (%) 35 46 59 82 55 77 1000 hrs EI Retention (%) 13 33 55 77 18 64 In all Tables: TS = tensile strength; EL = elongation to break

TABLE 2 Example C-6 C-7 C-8 C-9 C-10 2 PA6T/DT 63.75 62.75 61.75 64.25 64.25 61.75 TPE 1 2 3 2 Naugard ® 445 0.5 0.5 Chimassorb ® 944FDL 0.5 0.5 Wax OP 0.25 0.25 0.25 0.25 0.25 0.25 Glass Fiber D 35 35 35 35 35 35 AOA 210° C. TS (MPa) 0 h 218 218 215 228 220 221 TS (MPa) 500 h 186 220 213 128 144 223 TS (MPa) 1000 h 152 210 207 115 131 212  500 hrs TS Retention (%) 85 101 99 56 65 101 1000 hrs TS Retention (%) 70 96 96 50 60 96 EI (%) 0 h 2.2 2.2 2.2 2.2 2.2 2.2 EI (%) 500 h 1.8 2.2 2.2 1.2 1.5 2.2 EI (%) 1000 h 1.5 2.1 2.1 1.1 1.2 2.1  500 hrs EI Retention (%) 82 100 100 55 68 100 1000 hrs EI Retention (%) 68 95 95 50 55 95 AOA 230° C. TS (MPa) 0 h 218 218 215 228 220 221 TS (MPa) 500 h 135 158 177 88 98 178 TS (MPa) 1000 h 128 142 152 38 44 162  500 hrs TS Retention (%) 62 72 82 39 45 81 1000 hrs TS Retention (%) 59 65 71 17 20 73 EI (%) 0 h 2.2 2.2 2.2 2.2 2.2 2.2 EI (%) 500 h 1.2 1.7 1.7 0.9 0.7 1.8 EI (%) 1000 h 1.1 1.4 1.5 0.3 0.4 1.6  500 hrs EI Retention (%) 55 77 77 41 32 82 1000 hrs EI Retention (%) 50 64 68 14 18 73

Example 3 and C-11- C-14

Compositions of Examples 3 and Comparative Examples C-11-C-14 are listed in Table 3 for PA6T/66 compositions. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 3

Data in Table 3 indicates that Example 3 having 2 wt % DPE and 0.5 wt % Naijgard® 445 hindered amine has higher % retention of tensile strength than the Comparative Examples containing 2.0 wt % DPE alone; Naugard® 445 hindered amine alone; or a combination of Naugard® 445 hindered amine and Irganox® 1098 hindered phenol.

TABLE 3 Example C-11 C-12 C-13 C-14 3 PA6T/66 64.35 64.25 63.95 62.75 62.25 DPE 2.00 2.00 Naugard 445 0.50 0.50 0.50 Wax OP 0.25 0.25 0.25 0.25 0.25 Irganox 1098 0.30 Cu heat stabilizer 0.40 Glass Fiber D 35.00 35.00 35.00 35.00 35.00 AOA 210° C. TS (MPa) 0 h 202 205 204 202 201 TS (MPa) 500 h 135 132 128 185 207 TS (MPa) 1000 h 126 128 115 176 191  500 hrs TS Retention 67 64 63 92 103 (%) 1000 hrs TS Retention 62 62 56 87 95 (%) EI (%) 0 h 2.2 2.3 2.3 2.1 2.1 EI (%) 500 h 1.4 1.4 1.4 1.9 2.3 EI (%) 1000 h 1.2 1.1 1.1 1.8 2.0  500 hrs EI Retention 64 61 61 90 110 (%) 1000 hrs EI Retention 55 48 48 86 95 (%) AOA 230° C. TS (MPa) 0 h 202 205 204 202 201 TS (MPa) 500 h 131 75 88 162 184 TS (MPa) 1000 h 100 25 26 148 165  500 hrs TS Retention 65 37 43 80 92 (%) 1000 hrs TS Retention 50 12 13 73 82 (%) EI (%) 0 h 2.2 2.3 2.3 2.1 2.1 EI (%) 500 h 1.4 0.8 1.8 1.8 1.9 EI (%) 1000 h 1.0 0.3 0.3 1.5 1.6  500 hrs EI Retention 64 35 78 86 90 (%) 1000 hrs EI Retention 45 13 13 71 76 (%)

Example 4-7

Compositions of Examples 4-7 are listed in Table 4 for PA6T/66 compositions with various co-stabilizers in combination with 2 wt % TPE. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 4. Examples 4-7 all show unexpectedly high retention of tensile strength under AOA 230° C./1000 hour ageing as compared with C-11 having a conventional copper heat stabilizer.

TABLE 4 Example 4 5 6 7 PA6T/66 62.25 61.75 61.25 61.75 Chimassorb ® 944FD 0.50 TPE 2.00 2.00 2.00 2.00 Chimassorb ® 119FL 0.50 1.00 Naugard ® 445 0.50 0.50 0.50 0.50 Wax OP 0.25 0.25 0.25 0.25 Glass Fiber D 35.00 35.00 35.00 35.00 AOA 210° C. TS (MPa) 0 h 205 212 211 209 TS (MPa) 500 h 195 215 218 211 TS (MPa) 1000 h 192 214 210 210  500 hrs TS Retention (%) 95 101 103 101 1000 hrs TS Retention (%) 94 101 100 100 EI (%) 0 h 2.3 2.4 2.2 2.2 EI (%) 500 h 2.2 2.4 2.5 2.3 EI (%) 1000 h 2.2 2.4 2.4 2.2 AOA 230° C.  500 hrs EI Retention (%) 96 100 114 105 1000 hrs EI Retention (%) 96 100 109 100 TS (MPa) 0 h 205 212 211 209 TS (MPa) 500 h 185 214 209 211 TS (MPa) 1000 h 158 199 191 188  500 hrs TS Retention (%) 90 101 99 101 1000 hrs TS Retention (%) 77 94 91 90 EI (%) 0 h 2.3 2.4 2.2 2.2 EI (%) 500 h 1.9 2.3 2.3 2.2 EI (%) 1000 h 1.5 2.1 2.1 2.0  500 hrs EI Retention (%) 83 96 105 100 1000 hrs EI Retention (%) 65 88 95 91

Example 8-10

Compositions of Examples 8-10 are listed in Table 5 for PA6T/66 compositions with various co-stabilizers in combination with 2 wt % TPE. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 5.

TABLE 5 PExample 8 9 10 PA6T/66 61.25 61.75 61.25 Chimassorb ® 944FD 1.00 TPE 2.00 2.00 2.00 Chimassorb ® 119FL Naugard ® 445 0.50 0.50 0.50 Tinuvin ® 770DF 0.50 1.00 Wax OP 0.25 0.25 0.25 Glass Fiber D 35.00 35.00 35.00 AOA 210° C. TS (MPa) 0 h 212 202 201 TS (MPa) 500 h 225 208 208 TS (MPa) 1000 h 209 202 199  500 hrs TS Retention (%) 106 103 103 1000 hrs TS Retention (%) 99 100 99 EI (%) 0 h 2.3 2.2 2.2 EI (%) 500 h 2.4 2.2 2.3 EI (%) 1000 h 2.3 2.1 2.2  500 hrs EI Retention (%) 104 100 105 1000 hrs EI Retention (%) 100 95 100 AOA 230° C. TS (MPa) 0 h 212 202 201 TS (MPa) 500 h 215 208 207 TS (MPa) 1000 h 184 182 181  500 hrs TS Retention (%) 101 103 103 1000 hrs TS Retention (%) 87 90 90 EI (%) 0 h 2.3 2.2 2.2 EI (%) 500 h 2.2 2.3 2.3 EI (%) 1000 h 2 1.9 1.9  500 hrs EI Retention (%) 96 105 105 1000 hrs EI Retention (%) 87 86 86

Example 11-13 and C-15

Compositions of Examples 11-13 are listed in Table 6 for PA6T/66 compositions with various co-stabilizers in combination with 3 wt % DPE. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 5.

Examples 11-13 all show unexpected and surprising retention of tensile strength under AOA 230° C./1000hour ageing as compared with C-15 having a conventional copper heat stabilizer.

TABLE 6 Example 11 12 13 C-15 PA6T/66 61.25 60.75 60.75 64.35 Chimassorb ® 944FD 0.50 DPE 3.00 3.00 3.00 Chimassorb ® 119FL 0.50 Naugard ® 445 0.50 0.50 0.50 Wax OP 0.25 0.25 0.25 0.25 Cu heat stabilizer 0.40 Glass Fiber D 35.00 35.00 35.00 35.00 AOA 210° C. TS (MPa) 0 h 208 211 210 220 TS (MPa) 500 h 215 225 226 167 TS (MPa) 1000 h 209 215 218 134  500 hrs TS Retention (%) 103 107 108 76 1000 hrs TS Retention (%) 100 102 104 61 EI (%) 0 h 2.2 2.1 2.3 2.2 EI (%) 500 h 2.3 2.3 2.4 1.8 EI (%) 1000 h 2.2 2.2 2.3 1.3  500 hrs EI Retention (%) 105 110 104 82 1000 hrs EI Retention (%) 100 105 100 59 AOA 230° C. TS (MPa) 0 h 208 211 210 220 TS (MPa) 500 h 202 215 218 138 TS (MPa) 1000 h 181 214 211 98  500 hrs TS Retention (%) 97 102 104 63 1000 hrs TS Retention (%) 87 101 100 45 EI (%) 0 h 2.2 2.1 2.3 2.2 EI (%) 500 h 2.2 2.2 2.2 1.5 EI (%) 1000 h 1.9 2.2 2.2 1.0  500 hrs EI Retention (%) 100 105 96 68 1000 hrs EI Retention (%) 86 105 96 45

Comparative Examples C-16- C-20

Comparative Examples C-16- C-20 are listed in Table 7 for PA6T/66 compositions with various co-stabilizers, but without a polyhydric alcohol. Tensile properties after AOA at 210° C. and 230° C. at 500 h and 1000 h, and retention of physical properties are listed in Table 7. The various combinations of co-stabilizers fail to provide high retention of tensile strength under AOA at 230 C/1000 hours, as compared to the Examples 4-13. For instance Examples 4-13, having a combination of polyhydric alcohol and co-stabilizer, show retention of tensile strength of at least 77% in all examples at AOA of 230 C/1000 hours; whereas the comparative examples, show a maximum of only 44% under the same conditions.

TABLE 7 Example C-16 C-17 C-18 C-19 C-20 PA6T/66 64.25 63.75 63.25 63.75 63.3 Chimassorb ® 944FD 0.50 1.00 Chimassorb ® 119FL 0.50 1.00 Naugard ® 445 0.50 0.50 0.50 0.50 0.50 Wax OP 0.25 0.25 0.25 0.25 0.25 Glass Fiber D 35.00 35.00 35.00 35.00 35.00 AOA 210° C. TS (MPa) 0 h 222 221 218 216 215 TS (MPa) 500 h 138 133 138 121 88 TS (MPa) 1000 h 118 62 52 48 41  500 hrs TS Retention 62 60 63 56 41 (%) 1000 hrs TS Retention 53 28 24 22 19 (%) EI (%) 0 h 2.2 2.3 2.3 2.2 2.1 EI (%) 500 h 1.3 1.3 1.3 1.2 0.9 EI (%) 1000 h 1.1 0.6 0.5 0.5 0.5  500 hrs EI Retention 59 57 57 55 43 (%) 1000 hrs EI Retention 50 26 22 23 24 (%) AOA 230° C. TS (MPa) 0 h 222 221 218 216 215 TS (MPa) 500 h 125 118 109 94 71 TS (MPa) 1000 h 91 58 48 45 32  500 hrs TS Retention 56 53 50 44 33 (%) 1000 hrs TS Retention 41 26 22 21 15 (%) EI (%) 0 h 2.2 2.3 2.3 2.2 2.1 EI (%) 500 h 1.2 1.1 1.1 0.9 0.8 EI (%) 1000 h 0.9 0.6 0.5 0.5 0.3  500 hrs EI Retention 55 48 48 41 38 (%) 1000 hrs EI Retention 41 26 22 23 14 (%)

The Examples illustrate polyhydric alcohols in combination with co-stabilizers, added to reinforced polyamide compositions are an economically viable solution to the current need of having articles that are highly heat resistant upon long-term exposure in comparison with conventional heat stabilizers that lead either to poor heat aging resistant compositions or expensive ones. 

1. A molded or extruded thermoplastic article comprising a polyamide composition comprising (a) a polyamide resin having a melting point and/or glass transition; (b) 0.1 to 10 weight percent of one or more polyhydric alcohols having more than two hydroxyl groups and having a number average molecular weight (M_(n)) of less than 2000; (c) 0.1 to 3 weight percent of one or more co-stabilizer(s) having a 10% weight loss temperature, as determined by thermogravimetric analysis (TGA), of greater than 30° C. below said melting point of said polyamide resin if said melting point is present, or at least 250° C. if said melting point is not present; selected from the group consisting of secondary aryl amines and hindered amine light stabilizers (HALS), and mixtures thereof; (d) 10 to 60 weight percent of one or more reinforcement agents; and (e) 0 to 50 weight percent of a polymeric toughener comprising a reactive functional group and/or a metal salt of a carboxylic acid; wherein all weight percentages are based on the total weight of the polyamide composition; and wherein 4 mm test bars prepared from said polyamide composition, exposed at a test temperature at 170° C. for a test period of 500 hours, in an atmosphere of air, and tested according to ISO 527-2/1A, have a retention of tensile strength, on average, of at least 50 percent, as compared with that of an unexposed control of identical composition and shape.
 2. The molded or extruded thermoplastic article of claim 1 wherein herein said polyamide resin comprises a one or more polyamides independently selected from the group consisting of Group (I) Polyamides having said melting point of less than 210° C., and comprising an aliphatic or semiaromatic polyamide selected from the group poly(pentamethylene decanediamide) (PA510), poly(pentamethylene dodecanediamide) (PA512), poly(ε-caprolactam/hexamethylene hexanediamide) (PA6/66), poly(ε-caprolactarri/hexamethylene decanediamide) (PA6/610), poly(ε-caprolactam/hexamethylene dodecanediamide) (PA6/612), poly(hexamethylene tridecanediamide) (PA613), poly(hexamethylene pentadecanediamide) (PA615), poly(ε-caprolactam/tetramethylene terephthalamide) (PA6/4T), poly(ε-caprolactam/hexamethylene terephthalamide) (PA6/6T), poly(ε-caprolactam/decamethylene terephthalamide) (PA6/10T), poly(ε-caprolactam/dodecamethylene terephthalamide) (PA6/12T), poly(hexamethylene decanediamide/hexamethylene terephthalamide) (PA610/6T), poly(hexamethylene dodecanediamide/hexamethylene terephthalamide) (PA612/6T), poly(hexamethylene tetradecanediamide/hexamethylene terephthalamide) (PA614/6T), poly(ε-caprolactam/hexamethylene isophthalamide/hexamethylene terephthalamide) (PA6/61/6T), poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene decanediamide) (PA6/66/610), poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene dodecanediamide) (PA6/66/612), poly(ε-caprolactam/hexamethylene hexanediamide/hexanmethylene decanediamide/hexamethylene dodecanediamide) (PA6/66/610/612), poly(2-methylpentamethylene hexanediamide/hexamethylene hexanediamide/hexamethylene terephthamide) (PA D6/66//6T), poly(2-methylpentamethylene hexanediamide/hexamethylene hexanediamide/) (PA D6/66), poly(decamethylene decanediamide) (PA1010), poly(decamethylene dodecanediamide) (PA1012), poly(decamethylene decanediamide/decanmethylene terephthalamide) (PA1010/10T) poly(decamethylene decanediamide/dodecamethylene decanediamide/decamethylene terephthalamide/dodecamethylene terephthalamide (PA1010/121010T/12T), poly(11-aminoundecanamide) (PA11), poly(11-aminoundecanamide/tetramethylene terephthalamide) (PA111/4T), poly(11-aminoundecanamide/hexamethylene terephthalamide) (PA11/6T), poly(11-aminoundecanamide/decamethylene terephthalamide) (PA11/10T), poly(11-aminoundecanamide/dodecamethylene terephthalamide) (PA11112T), poly(12-aminododecanamide) (PA12), poly(12-aminododecanamide/tetramethylene terephthalamide) (PA12/4T), poly(12-aminododecanamide/hexamethylene terephthalamide) (PA12/6T), poly(12-aminododecanamide/decamethylene terephthalamide) (PA12/10T) poly(dodecamethylene dodecanediamide) (PA1212), and poly(dodecamethylene dodecanediamide/dodecamethylene dodecanediamide/dodecamethylene terephthalamide)) (PA1212/12T); Group (II) Polyamides having said melting point of at least 210° C., and comprising an aliphatic polyamide selected from the group consisting of poly(tetramethylene hexanediamide) (PA46), poly(ε-caprolactam) (PA 6), poly(hexamethylene hexanediamide/(ε-caprolactam/) (PA 66/6) poly(hexamethylene hexanediamide) (PA 66), poly(hexamethylene hexanediamide/hexamethylene decanediamide) (PA66/610), poly(hexamethylene hexanediamide/hexamethylene dodecanediamide) (PA66/612), poly(hexamethylene hexanediamide/decamethylene decanediamide) (PA66/1010), poly(hexamethylene decanediamide) (PA610), poly(hexamethylene dodecanediamide) (PA612), poly(hexamethylene tetradecanediamide) (PA614), poly(hexamethylene hexadecanediamide) (PA616), and poly(tetramethylene hexanediamide/2-methylpentamethylene hexanediamide) (PA46/D6); Group (III) Polyamides having said melting point of at least 210° C., and comprising (aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: i. aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and (bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: ii. an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; iii. a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; Group (IV) Polyamides comprising (cc) about 50 to about 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and (dd) about 5 to about 50 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; Group (V) Polyamides having said melting point of at least 260° C., and comprising (ee) greater than 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; (ff) less than 5 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; and Group (VI) Polyamides having no melting point, and selected from the group consisting of poly(hexamethylene isophthalamide/hexamethylene terephthalamide) (61/6T) and poly(hexamethylene isophthalamide/hexamethylene terephthalamide/hexamethylene hexanediamide) (6116T166).
 3. The molded or extruded thermoplastic article of claim 2 wherein said polyamide resin comprises a blend of two or more polyamides selected from the group consisting of Group (I) and Group (II) Polyamides; Group (I) and Group (III) Polyamide, Group (I) and Group (VI) Polyamides, Group (II) and Group (III) Polyamides, Group (II) and Group (IV) Polyamides, Group (II) and Group (V) Polyamides, Group (II) and Group (VI) Polyamides, Group (III) and Group (VI) Polyamides, and Group (IV) and Group (V) Polyamides.
 4. The molded or extruded thermoplastic article of claim 3 wherein said polyamide resin comprises a blend of Group (II) and Group (V) Polyamide.
 5. The molded or extruded thermoplastic article of claim 3 wherein said polyamide resin comprises a blend of Group (II) and Group (III) Polyamide.
 6. The molded or extruded thermoplastic article of claim 3 wherein said polyamide resin comprises a blend of Group (III) and Group (VI) Polyamide.
 7. The molded or extruded thermoplastic article of claim 1 wherein the polyhydric alcohol is selected fro the group consisting of pentaerythritol, dipentaerythritol, tripentaerythritol, di-trimethylopropane, D-mannitol, D-sorbitol and xylitol.
 8. The molded or extruded thermoplastic article of claim 1 wherein the one or more co-stabilizer(s) is one or more secondary aryl amines.
 9. The molded or extruded thermoplastic article of claim 1 wherein the one or more reinforcement agents is selected from the group consisting calcium carbonate, glass fibers with circular and noncircular cross-section, glass flakes, glass beads, carbon fibers, talc, mica, wollastonite, calcined clay, kaolin, diatomite, magnesium sulfate, magnesium silicate, barium sulphate, titanium dioxide, sodium aluminum carbonate, barium ferrite, potassium titanate and mixtures thereof.
 10. The molded or extruded thermoplastic article of claim 1 wherein said polyamide composition comprises less than 25 ppm copper as determined with atomic absorption spectroscopy.
 11. The molded or extruded thermoplastic article of claim 1 selected from the group consisting of charge air coolers; cylinder head covers; oil pans; engine cooling systems, thermostat and heater housings, coolant pumps, mufflers, housings for catalytic converters; air intake manifolds; and timing chain belt front covers.
 12. A molded or extruded thermoplastic article comprising a polyamide composition comprising (a) a polyamide resin having a melting point and/or glass transition; (b) 0.1 to 10 weight percent of one or more polyhydric alcohols having more than two hydroxyl groups and having a number average molecular weight (M_(n)) of less than 2000; (c) 0.1 to 3 weight percent of one or more co-stabilizer(s) having a 10% weight loss temperature, as determined by thermogravimetric analysis, of greater than 30° C. below said melting point of said polyamide resin if said melting point is present, or at least 250° C. if said melting point is not present; selected from the group consisting of secondary aryl amines and hindered amine light stabilizers, and mixtures thereof; (d) 10 to 60 weight percent of one or more reinforcement agents; and (e) 0 to 50 weight percent of a polymeric toughener comprising a reactive functional group and/or a metal salt of a carboxylic acid; wherein all weight percentages are based on the total weight of the polyamide composition; and wherein molded 4 mm test bars prepared from said polyamide composition, and exposed a test temperature at 210° C. for a test period of 500 hours, in an atmosphere of air, and tested according to ISO 527-2/1A, have, on average, a retention of tensile strength of at least 50 percent, as compared with that of an unexposed control of identical composition and shape.
 13. The molded or extruded thermoplastic article of claim 12 wherein said polyamide resin comprises a one or more polyamides independently selected from the groups consisting of Group (II) polyamides having said melting point of at least 210° C., and comprising an aliphatic polyamide selected from the group consisting of poly(tetramethylene hexanediamide) (PA46), poly(ε-caprolactam) (PA 6), poly(hexamethylene hexanediamide/(ε-caprolactam/) (PA 66/6) poly(hexamethylene hexanediamide) (PA 66), poly(hexamethylene hexanediamide/hexamethylene decanediamide) (PA66/610), poly(hexamethylene hexanediamide/hexamethylene dodecanediamide) (PA66/612), poly(hexamethylene hexanediamide/decamethylene decanediamide) (PA66/1010), poly(hexamethylene decanediamide) (PA610), poly(hexamethylene dodecanediamide) (PA612), poly(hexamethylene tetradecanediamide) (PA614), poly(hexamethylene hexadecanediamide) (PA616), and poly(tetramethylene hexanediamide/2-methylpentamethylene hexanediamide) (PA46/D6); Group (III) Polyamides having said melting point of at least 210° C., and comprising (aa) about 20 to about 35 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and (bb) about 65 to about 80 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and (ii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; and Group (IV) Polyamides comprising (cc) about 50 to about 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and (dd) about 5 to about 50 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; Group (V) Polyamides having said melting point of at least 260° C., and comprising (ee) greater than 95 mole percent semiaromatic repeat units derived from monomers selected from one or more of the group consisting of: (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms; and (ff) less than 5 mole percent aliphatic repeat units derived from monomers selected from one or more of the group consisting of: (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20 carbon atoms; and (iii) a lactam and/or aminocarboxylic acid having 4 to 20 carbon atoms; and Group (VI) Polyamides having no melting point, and selected from the group consisting of poly(hexamethylene isophthalamide/hexamethylene terephthalamide) (61/6T) and poly(hexamethylene isophthalamide/hexamethylene terephthalamide/hexamethylene hexanediamide) (61/6T/66).
 14. The molded or extruded thermoplastic article of claim 12 wherein the one or more co-stabilizer(s) is one or more secondary aryl amines.
 15. The molded or extruded thermoplastic article of claim 13 wherein said polyamide resin comprises a blend of two or more polyamides selected from the group consisting of Group (II) and Group (III) Polyamides, Group (II) and Group (IV) Polyamides, Group (II) and Group (V) Polyamides, Group (II) and Group (VI) Polyamides, Group (III) and Group (VI) Polyamides, and Group (IV) and Group (V) Polyamides. 